Gas burner for dryer

ABSTRACT

Gas burner for a dryer including a gas nozzle for receiving, and injecting gas, a mixing tube for mixing the gas injected from the gas nozzle and primary air, igniter fitted to an outlet of the mixing tube for igniting the gas mixed with the primary air coming out of the outlet of the mixing tube, and a flame holder fitted to the outlet of the mixing tube having flame holes for splitting, and ejecting the gas mixed with the primary air in burning the gas, thereby forming shorter flame lengths, and securing stability of the flame by enhancing an initial igniting capability, and splitting the flame into many parts to increase introduction of secondary air into the flame.

TECHNICAL FIELD

The present invention relates to a dryer, and more particularly, to agas burner for burning gas to produce heated air for drying objectsintroduced into a drum.

BACKGROUND ART

In general, the dryer dries objects, such as clothes, and the like, withair heated by electric heater, or a gas burner.

FIG. 1 illustrates a perspective disassembled view of key parts of arelated art dryer. Referring to the drawing, there is a drum 1 fittedinside of a cabinet (not shown) that forms an outside shape of thedryer. The drum 1 is cylindrical, with opposite opened ends, and has abelt groove 2 along an outside circumference of a middle of the drum 1for winding a drum belt 4 driven by a motor 3. The drum 1 has a dryingchamber 5 therein for carrying out drying. The drum 1 has a plurality oflifters 6 therein for lifting and dropping drying objects in the dryingchamber 5, to turn the drying objects upside down for improving a dryingefficiency when the drum 1 is rotated.

The drum 1 is provided with a front supporter 7 and a rear supporter 9fitted to a front end and a rear end thereof, oppositely. The frontsupporter 7 and the rear supporter 9 close opened parts of the drum 1,to form the drying chamber 5, and support the front end and the rear endof the drum 1. There are sealing members 10 fitted between the frontsupporter 7 and the drum 1 to be rotated, and the rear supporter 9 andthe drum 1 to be rotated for prevention of leakage. Of course, there area plurality of rollers (not shown) provided at required positions of thefront supporter 7 and the rear supporter 9 of the drum 1, for supportingthe drum 1.

The front supporter 7 has an opening 8 for making inside and outside ofthe drying chamber 5 in communication. The opening 8 is selectivelyopened by a door (not shown).

The rear supporter 9 is fitted with a heated air supply duct 12, incommunication with the drying chamber 5, for serving as a passage forsupplying heated air to the drying chamber 5.

There is an outlet assembly 13 at one side of the front supporter 7 at abottom of the opening 8 of the front supporter 7, for escaping of air.The outlet assembly 13 is provided with a lint filter 14.

The lint filter 14 filters foreign matters (for example, lint and dust)contained in the air escaping from the drying chamber 5.

There is a lint duct 15 in communication with the outlet assembly 13,wherein the lint filter 14 is positioned even inside of the lint duct15. There is a blower 17 connected to the lint duct 15, for drawing airfrom inside of the drying chamber 5 through the lint duct 15. The blower17 is fitted to an inside of a blower housing 18 having one side incommunication with the lint duct 15 and the other side connected to anair discharge pipe 19. Therefore, the air, escaped from the dryingchamber 5 and passed through the lint duct 15, is discharged to anoutside through the air discharge pipe 19 by the blower 17.

In the meantime, there is a guide funnel 20 connected to an inlet of theheated air supply duct 12. The guide funnel 20 guides the heated airproduced by burning the gas to the inlet of the heated air supply duct.There is a mixing tube 24 at the inlet of the guide funnel 20 for mixingthe gas injected from the gas nozzle 22 with primary air. The mixingtube 24 has an outlet positioned a distance inside of the guide funnel20.

The gas nozzle 22 is fitted opposite to the inlet of the mixing tube 24,and has a valve 30 connected thereto for controlling gas supply and anamount of the gas supply. The valve 30 has a gas tube 23 connectedthereto for continuous supply of gas from a gas supply source.

Accordingly, the gas injected from the gas nozzle 22 and external airintroduced through the inlet of the mixing tube 24, i.e., the primaryair, are mixed inside of the mixing tube 24.

The operation of the foregoing related art dryer will be explained.

Upon pressing a starting button after laundry, drying objects, isintroduced into the drying chamber 5 in the drum 1, and a door thereonis closed, the drum 1 starts to rotate as the drum belt 4 wound aroundthe belt groove 2 is driven by the motor 3. As the blower 17 starts, theair inside of the drying chamber 5 is drawn through the lint duct 15.Then, external air is introduced into the drying chamber 5 through theair supply duct 12 owing to a pressure difference.

The air to the heated air supply duct 12 is heated to a relatively hightemperature by the gas burner. The gas is injected to an inside of themixing tube 24 through the gas nozzle 22, the primary air is introducedto the inlet of the mixing tube 24, the gas and the primary air aremixed in the mixing tube 24, and ignited at the outlet of the mixingtube 24 by a spark plug 26 initially, thereby burned. A thermal energygenerated as the gas is burned is introduced into the guide funnel 20,and heats the introduced air, to produce the heated air.

Meanwhile, the heated air is introduced into the drying chamber 5 in thedrum 1 through the heat air supply duct 12. The heated air absorbs moistin laundry in the drying chamber 5, and escapes the drying chamber 5through the outlet assembly 13. The air is made to escape the dryingchamber 5 through the outlet assembly by a suction force of the blower17. The foreign matters, such as dust, and lint in the air escapingthrough the outlet assembly 13 are filtered at the lint filter 14.

However, the foregoing related art has the following problems.

The single circular sectioned outlet of the mixing tube 24 causes toform one large and long flame as shown in FIG. 3 at the outlet of themixing tube 24. The flame differs in size, length, and position offormation of the flame depending on a number of revolution of theblower, air resistance, and the like.

For an example, when the blower 17 has an appropriate number ofrevolution, though the flame ‘F’ is formed close to the outlet of themixing tube 24, when the blower 17 has an excessively high number ofrevolution, a lifting phenomenon is occurred in which the flame ‘F’ isformed at a point a distance ‘1’ away from the outlet of the mixing tube24.

When the blower 17 runs at an excessively low number of revolutions, theflame ‘F’ becomes very long, such that the flame reaches to the heatedair supply duct, and heats the heated air supply duct excessively, and,to the drying chamber 5 and starts fire when the flame becomesexcessively long.

In other words, in the related art, if external conditions, such as thenumber of revolutions of the blower, and the like are not appropriate, abalance between a combustion rate of the gas and an amount of introducedair is broken, to cause lifting, or the flame to reach to an inside ofthe drum as the flame becomes excessively long.

Moreover, when the flame becomes longer, entire heat can not be used forheating the air, but much of the heat is taken away by adjacentcomponents as the flame reaches close to the adjacent components, thatincreases heat loss.

In the related art, the initial ignition capability is poor because thegas mixed with the primary air exits the outlet of the mixing tube 24right away.

The single circular sectioned outlet of the mixing tube 24 causes theflame ‘F’ to have a form of a lump, which reduces a contact area of theflame ‘F’ with the secondary air. That is, if the flame ‘F’ has the formof a lump, the contact area of the flame ‘F’ with the secondary air isreduced on the whole, to cause incomplete combustion as there is lack ofair at an inner part of the flame, that also acts as a cause of a longflame.

Moreover, the insufficient secondary air supply to the flame ‘F’ causesthe flame, not only to become longer, but also to turn yellowish, withincomplete combustion, to produce much soot and hazardous gases (CO,NOx, SOx).

DISCLOSURE OF INVENTION

An object of the present invention is to provide a gas burner for adryer which can improve an ignition characteristic by improving aninitial ignition capability.

Another object of the present invention is to provide a gas burner for adryer which can improve flame characteristics such that formation of theflame is stable.

For achieving the object of the present invention, there is provided agas burner for a dryer including a gas nozzle for receiving and sprayinga gas, a mixing tube for mixing the gas sprayed from the gas nozzle andprimary air, an igniter fitted to an outlet side of the mixing tube forigniting the gas mixed with the primary air passed through the outlet ofthe mixing tube, and a flame holder fitted to an outlet side of themixing tube having flame holes for making the gas mixed with the primaryair to be split, and sprayed in the burning.

The flame holes in the flame holder may include a central flame holepart, and a plurality of spiral flame hole parts in communication with,and around the central flame hole.

In the meantime, in another aspect of the present invention, the flameholes in the flame holder may include a central circular flame hole, anda plurality of fan shaped flame holes prolonged in a circumferentialdirection around the circular flame hole, in addition to the circularflame hole.

Or, in another aspect of the present invention, the flame holes in theflame holder may be circular flame holes arranged in a radial directionfrom a central part of a surface of the flame holder to for concentriccircles.

That is, the flame holes in the flame holder may be one pass throughhole in communication with others, or a plurality of pass through holeshaving geometrical forms the same or different from one another, and maybe concentric if the geometrical forms are the same.

The flame holder may be rotatably fitted to an inside of an outlet sideof the mixing tube.

In another aspect of the present invention, the flame holder includesslit forms of flame holes arranged in a radial direction in a surface ofthe flame holder, and a plurality of rectangular flame holes in aperiphery of the flame holder along a circumferential direction thereof.

Along with this, the flame holder further includes a central circularflame hole, and a plurality of circular flame holes between the slitforms of flame holes in a radial direction at fixed intervals to beconcentric with respect to the central circular flame hole. Theplurality of circular flame holes between the central circular flamehole of the flame holder and the slit forms of flame holes have the samediameters, but the central circular flame hole of the flame holder andthe circular flame holes in an outer part thereof may have differentdiameters.

The mixing tube has a structure in which a flow passage substantiallybecomes the smaller as it goes from an inlet side to an outlet side, andthen becomes gradually the larger at a fixed ratio again, and includesan enlarged part at the outlet side of the mixing tube having the flowpassage enlarged suddenly, and a flame holder fitted to an inside of theenlarged part. The enlarged part at the outlet side of the mixing tubeis formed as one unit with the mixing tube, or as a detachable separatepiece.

The mixing tube preferably is fitted upward at an angle with referenceto a horizontal plane as it goes from an inlet side to an outlet side.

The flame holder may be rotatably fitted to an inside of an outlet ofthe mixing tube.

In another aspect of the present invention, the flame holder issemispherical, and includes a circular flame hole in a central part of asurface thereof, and slit forms of flame holes in a radial directionaround the circular flame hole.

In this instance, the slit form of the flame hole has a form of a convexlens seen from a side, or a crescent geometrically.

Along with this, the flame holder further includes flame sustainingcircular flame holes between the radial slit forms of flame holes havingdiameters smaller than the central flame hole.

In this instance, the flame sustaining circular flame holes between theradial slit forms of flame holes have the same diameters.

The flame sustaining circular flame holes between the radial slit formsof flame holes are positioned at ends between the slit forms of flameholes.

The mixing tube is preferably fitted upward at an angle with referenceto a horizontal plane as it goes from an inlet side to an outlet side.

The flame holder may be fitted to an inside of an outlet side of themixing tube, or so as to be located in front of the outlet of the mixingtube a distance away therefrom.

The flame holder may be rotatably fitted to an inside of the mixingtube.

In another aspect of the present invention, the flame holder includes anannular hub having a central circular flame hole, and a plurality ofblades on an outer circumference of the hub along a circumferentialdirection thereof at fixed intervals.

The blade is twisted at an angle with respect to a hub plane.

In the meantime, the flame holder is fitted so as to be located in frontof the outlet of the mixing tube as a holding part extended from oneside of the hub is fixed to an outlet side of the mixing tube.

The mixing tube is preferably fitted upward at an angle with referenceto a horizontal plane as it goes from an inlet side to an outlet side.

In the meantime, in another aspect of the present invention, the flameholder is of a “┐” formed plate structure having a vertical face and ahorizontal face, the vertical face having a central flame hole, andsidewall faces at both edges thereof each extended backward to rear ofthe flame holder to form a width.

The sidewall faces at opposite edges of the vertical face of the flameholder are formed by cutting opposite side parts of an edge where thevertical face and the horizontal face meet, and bending the oppositeside parts backward.

The flame holder is fitted so as to be located in front of an outlet ofthe mixing tube as a holding part extended from one side of thehorizontal face is fixed to an outlet side of the mixing tube.

In the meantime, in another aspect of the present invention, the flameholder includes an annular hub having a central flame hole, and aplurality of blades on an outer circumference thereof along acircumferential direction at fixed intervals.

The annular hub is convexed forward.

The blade includes a backward bent part at a fore end thereof at anangle ranging 10–30 degrees with respect to an axis direction passingthrough the hub.

In the meantime, the blades include at least one blade having a longerarc than the other blades formed in one side circumference of the hub.

The flame holder is fitted so as to be located in front of an outlet ofthe mixing tube as a holding part extended from one side of thehorizontal face is fixed to an outlet side of the mixing tube.

The flame holder is rotatably fitted to an inside of an outlet of themixing tube.

The mixing tube is fitted upward at an angle with reference to ahorizontal plane as it goes from an inlet side to an outlet side.

Thus, the foregoing gas burner for a dryer of the present inventionimproves an initial ignition performance, shortens an entire length of aflame, facilitates introduction of more air into the flame, to form astable blue flame having a high temperature.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a perspective disassembled view of key parts of arelated art dryer;

FIG. 2 illustrates a plan view of a related art gas burner for a dryer;

FIG. 3 explains problems of a related art gas burner for a dryer;

FIG. 4 illustrates a perspective disassembled view of gas burner for adryer in accordance with a first preferred embodiment of the presentinvention;

FIG. 5 illustrates one in accordance with a second preferred embodimentof the present invention, showing a front view of an outlet side of amixer seen from ‘A’ direction in FIG. 4;

FIG. 6 illustrates a front view of an outlet side of a mixer inaccordance with a third preferred embodiment of the present invention;

FIG. 7 illustrates a perspective disassembled view of gas burner for adryer in accordance with a fourth preferred embodiment of the presentinvention;

FIG. 8 illustrates a front view of an outlet side of a mixer seen from‘A’ direction in FIG. 7;

FIG. 9 illustrates a front view only of the flame holder in FIG. 8;

FIG. 10 illustrates a perspective disassembled view of gas burner for adryer in accordance with a fifth preferred embodiment of the presentinvention;

FIG. 11A illustrates a perspective view of an outlet side of a mixingtube seen from ‘A’ direction in FIG. 10;

FIG 11B illustrates a perspective view of an outlet side of a mixingtube seen from ‘A’ direction in FIG. 10, showing another embodiment ofthe flame holder;

FIG. 12 illustrates a perspective disassembled view of gas burner for adryer in accordance with a sixth preferred embodiment of the presentinvention;

FIG. 13A illustrates a perspective view of an outlet side of a mixingtube seen from ‘B’ direction in FIG. 12;

FIG. 13B illustrates a perspective view of an outlet side of a mixingtube seen from ‘B’ direction in FIG. 12, showing another embodiment ofthe flame holder;

FIG. 14 illustrates a perspective disassembled view of gas burner for adryer in accordance with a seventh preferred embodiment of the presentinvention;

FIG. 15 illustrates a perspective view of an outlet side of a mixer seenfrom ‘A’ direction in FIG. 14;

FIG. 16 illustrates a perspective disassembled view of gas burner for adryer in accordance with an eighth preferred embodiment of the presentinvention;

FIG. 17 illustrates a perspective view of an outlet side of a mixingtube seen from ‘A’ direction in FIG. 16;

FIG. 18 illustrates a perspective disassembled view of gas burner for adryer in accordance with a ninth preferred embodiment of the presentinvention;

FIG. 19 illustrates a front view of an outlet side of a mixer seen from‘A’ direction in FIG. 18;

FIG. 20 illustrates a perspective view of an outlet side of a mixingtube seen from ‘A’ direction in FIG. 18;

FIG. 21 illustrates a perspective, disassembled, back side view of FIG.20; and

FIG. 22 illustrates a section of a flame holder across a line I—I inFIG. 19.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of a gas burner for a dryer of the presentinvention, examples of which are illustrated in the accompanyingdrawings, will be explained in detail in an order of embodiments, withreference to the attached drawings. Parts identical to the related artwill be given the same reference symbol with the related art.

FIG. 4 illustrates a perspective disassembled view of gas burner for adryer in accordance with a first preferred embodiment of the presentinvention, FIG. 5 illustrates one in accordance with a second preferredembodiment of the present invention, showing a front view of an outletside of a mixer seen from ‘A’ direction in FIG. 4, and FIG. 6illustrates a front view of an outlet side of a mixer in accordance witha third preferred embodiment of the present invention.

Referring to FIG. 4, there is a gas tube 32 connected to a gas nozzle 30which sprays gas for combustion. The gas nozzle 22 has a valve 30 fittedthereto for controlling spray of gas received through the gas tube 32,and a spray amount of the spray when the gas is sprayed.

There is a mixing tube 24 in front of the gas nozzle 22. The mixing tube24 has a mixing passage 240 therein for mixing the gas from the gasnozzle 22 and primary air. The mixing tube 24 has a section designedsuch that a flow passage sectional area of the mixing tube 24 becomesthe smaller as it goes from an inlet side to an outlet side, and thenbecomes gradually the larger, again. The gas sprayed from the gas nozzle22 and the primary air enter into the inlet of the mixing tube 24.

There is an igniter 50 at an outlet side of the mixing tube 24 forigniting the gas from the mixing passage 240 of the mixing tube 24. Theigniter 50 of ceramic is heated as a current is provided thereto, andignites the gas mixed, and discharged with the primary air.

There is a flame holder 60 at an outlet side of the mixing tube 24. Itis preferable that the flame holder 60 is fitted to an outlet side ofthe mixing tube 24 perpendicular to a flow direction of the gas. Theflame holder 60 is a disk with an area the same with a sectional area ofthe flow passage of a fore end of the mixing tube, and has flame holesin a face thereof for spraying the gas mixed with the primary air.

The flame holder 60 has a substantially circular flame hole 62 in acentral part thereof, and a plurality of spiral flame holes 64 aroundthe circular flame hole 62 in communication therewith each having alength in a substantially radial direction. It is preferable that aratio of areas of the circular flame hole 62 and the spiral flame holes64 is set by an experiment.

Both the spiral flame holes 64 and the central circular flame hole 62spray the gas mixed with the primary air received through the mixingpassage 240, and form a main flame.

In the present invention, the main flame is split into a plurality offlames by the spiral flame holes 64 which are in communication, but hasa form of hole split into a plurality of holes, such that the flame hasa larger surface area on the whole, for receiving secondary air supply,more smoothly.

In the meantime, the mixing tube 24 is fitted upward at an angle as itgoes from the inlet side to the outlet side with respect to a horizontalplane, so that a tube axis direction of the mixing tube is in agreementwith a direction of flame in advance.

Next, FIG. 5 illustrates a second preferred embodiment of the presentinvention. The embodiment in FIG. 5 has a flame holder 160 fitted to anoutlet side of the mixing passage 41 of the mixing tube 40 differentfrom the first embodiment.

That is, the flame holder 160 has a central circular flame hole 162 witha diameter, and a plurality of fan shaped flame holes 164 around thecircular flame hole 162 each with a width enlarged in a radialdirection. The fan shaped flame holes 164 are separate from the circularflame hole 162.

FIG. 6 illustrates a third preferred embodiment of the presentinvention. In the embodiment shown in FIG. 6, the flame holder 260fitted to a downstream of the mixing passage 41 of the mixing tube 40has a plurality of same diametered circular flame holes 262 of forms ofpass through holes for spraying gas mixed with primary air as the gasflows through the mixing passage 41. When the gas is sprayed to outsideof the mixing passage 41, the plurality of circular flame holes 262facilitate spray of the gas separate for each of the flame holes, toform flames, separately.

The flame holder 160, or 260 shown in FIG. 5, or 6 respectively may alsobe rotatably fitted to an inside of the outlet side of the mixing tube.That is, the flame holder 60 may be fitted so as to be kept to rotateduring operation by a separate driving source (not shown) so that thegas sprayed through the flame holder 60 forms turbulence.

The operation of the foregoing first to third embodiment of the presentinvention will be explained, with reference to the embodiment shown inFIG. 4.

For having a drying process progressed in a dryer, it is required toelevate a temperature of air introduced into the drying chamber 5 as thegas is burned. For this, burning gas is sprayed into the mixing tube 24through the gas nozzle 22.

Along with the gas, primary air is introduced into the mixing tube 24.Accordingly, the gas and the primary air are mixed, and flow along thepassage inside of the mixing tube 24.

Then, the gas (i.e., a mixed gas) mixed with the primary air as the gasand the primary air flow along the inside passage of the mixing tube 24is split, and sprayed through the flame holes 62 or 64 of the flameholder 60 fitted to the outlet side of the mixing tube 24. The mixed gassprayed thus is ignited as the mixed gas receives heat from the igniter50 provided adjacent to the flame holder 60.

Then, drying hot air is produced continuously as combustion is made asthe mixed gas is kept sprayed through the flame holes in the flameholder 60 in a split state. The flame formed by the combustion of gas issplit into a plurality of flames through the circular flame hole 62 andthe spiral flame holes 64, (especially, the spiral flame holes).

According to this, in the present invention, a total flame lengthbecomes short, and a contact area with the secondary air is increased.

That is, as the mixed gas discharged through the outlet side of themixing tube 24 is split through the flame holes 62, or 64 in the flameholder 60, an entire length of the flame becomes short, and more amountof secondary air is introduced to the split short flames, with anincreased mixing effect of the flames with the air, thereby achieving aperfect combustion, with blue flames in a stable flame state.

In other words, as the flame is split into a plurality of flames, anentire surface area of the flames is increased, with a relativelyincreased contact area with ambient air, i.e., the secondary air, thecombustion of gas is made more effectively, to achieve the perfectcombustion.

Moreover, the flame holder 60 divides between an inside and an outsideof the mixing tube 24, to prevent a reverse direction flame, and toprevent the flame from becoming unstable by an external influence.

Thus, as the flame is shortened, and the perfect combustion is made, thepresent invention can prevent the lifting in which an ignition point ofthe flame is positioned far from an outlet of the mixing tube 24, andthe overheating of the air to be supplied to the drying chamber 5 inadvance.

Meanwhile, in the drying process again, the external air introduced intoan inside of the guide funnel 20 is heated, and turned into heated airas the gas is burned thus, and introduced into the drying chamber 5through the hot air supply duct 12.

The hot air introduced into the drying chamber 5 inside of the drum 1absorbs moist contained in laundry, passes through the lint filter 14again, and is blown toward the discharge pipe 19 by the blower 17through the lint duct 15.

In the meantime, the flame holder 60 may be rotatably fitted to aninside of the outlet side of the mixing tube 24. That is, the flameholder 60 may be provided with an additional driving source (not shown)for continuous rotation during operation, so that the gas sprayedthrough the flame holder 360 forms a turbulence.

A gas burner for a dryer in accordance with a fourth preferredembodiment of the present invention will be explained in detail, withreference to the attached drawings. Parts identical to the related artwill given the same reference symbols in the explanation.

FIG. 7 illustrates a perspective disassembled view of gas burner for adryer in accordance with a fourth preferred embodiment of the presentinvention, FIG. 8 illustrates a front view of an outlet side of a mixerseen from ‘A’ direction in FIG. 7, and FIG. 9 illustrates a front viewonly of the flame holder in FIG. 8.

Referring to FIGS. 7–9, there is a gas tube 32 connected to a gas nozzle30 which sprays gas for combustion. The gas nozzle 22 has a valve 30fitted thereto for controlling spray of gas received through the gastube 32, and a spray amount of the spray when the gas is sprayed.

There is a mixing tube 24 in front of the gas nozzle 22. The mixing tube24 has a mixing passage 240 therein for mixing the gas from the gasnozzle 22 and primary air. The mixing tube 24 has section designed suchthat a flow passage sectional area of the mixing tube 24 becomes thesmaller as it goes from an inlet side to an outlet side, and thenbecomes gradually the larger, again. The gas sprayed from the gas nozzle22 and the primary air enter into the inlet of the mixing tube 24.

There is an igniter 50 at an outlet side of the mixing tube 24 forigniting the gas from the mixing passage 240 of the mixing tube 24. Theigniter 50 of ceramic is heated as a current is provided thereto, andignites the gas mixed, and discharged with the primary air. The igniter50 is either fitted to the mixing tube 24, or supported separately.

There is a flame holder 360 at an outlet side of the mixing tube 24. Itis preferable that the flame holder 360 is fitted to an outlet side ofthe mixing tube 24 perpendicular to a flow direction of the gas. Theflame holder 360 is a disk with an area the same with a sectional areaof an enlarged part 24 a of the flow passage at a fore end of the mixingtube, and has a variety of forms of flame holes in a face thereof forspraying the gas mixed with the primary air.

That is, the flame holder 360 has a plurality of slit form of flameholes 364 in a face thereof in a radial direction thereof, and aplurality of rectangular form of flame holes in a periphery thereofalong a circumference.

It is preferable that the flame holder 360 has a circular flame hole 362in a central part thereof, and a plurality of circular flame holes 362spaced fixed distances in a radial direction concentric to the circularflame hole 362 in the central part of the face between the slit form offlame holes 364 formed in a radial direction. The circular flame hole362 is pass through hole with a fix diameter.

The circular flame holes 362 between the slit form of flame holes 364have the same diameters, but the flame hole in the central part of theface of the flame holder 360 may have a diameter different from theflame holes in an outer part thereof.

It is preferable that ratios of areas of the circular flame holes 362,the slit form of flame hole 364, and the rectangular flame holes 363 areset by an experiment.

The circular flame holes 362, the slit form of flame hole 364, and therectangular flame holes 363 spray the gas mixed with the primary airreceived through the mixing passage 240, and form a main flame.

In the present invention, owing to the enlarged part 24 a having a flowpassage enlarged suddenly at the outlet side of the mixing tube 24, andthe flame holder 360 having a plurality of flame holes on an inner sidethereof, an initial ignition capability is enhanced since a speed of gasescaping from the flame holes in the flame holder 360 can be maintainedto an appropriate level.

Moreover, in the present invention, as the main flame is split into aplurality of flames by the plurality of slit form of flame holes 364 andcircular flame holes 363, with an increased surface area of the flame onthe whole, supply of the secondary air becomes more smooth. Especially,the concentric circular flame holes 362 serves to sustain the mainflame.

In the meantime, the mixing tube 24 is fitted tilted upward at an angleas it goes from the inlet side to the outlet side, so that a tube axisdirection of the mixing tube is in agreement with a direction of flamein advance.

The fourth embodiment of the present invention will be explained, withreference to the embodiment shown in FIGS. 7–9.

For having a drying process progressed in a dryer, it is required toelevate a temperature of air introduced into the drying chamber 5 as thegas is burned. For this, burning gas is sprayed into the mixing tube 24through the gas nozzle 22.

Along with the gas, primary air is introduced into the mixing tube 24.Accordingly, the gas and the primary air are mixed, and flow along thepassage inside of the mixing tube 24.

Then, the gas (i.e., a mixed gas) mixed with the primary air as the gasand the primary air flow along the inside passage of the mixing tube 24is split, and sprayed through the flame holes 362, 363, or 364 of theflame holder 360 fitted to the outlet side of the mixing tube 24. Themixed gas sprayed thus is ignited as the mixed gas receives heat fromthe igniter 50 provided adjacent to the flame holder 360.

Then, drying hot air is produced continuously as combustion is made, asthe mixed gas is kept sprayed through the flame holes in the flameholder 360 in a split state. In this instance, the flame formed by thecombustion of gas is split into a plurality of flames by the slit formof flame holes 364, the rectangular flame holes 363, and the concentricflame holes 362.

According to this, in the present invention, a total flame lengthbecomes shorter, and a contact area with the secondary air becomeslarger.

That is, as the mixed gas discharged through the outlet side of themixing tube 24 is split through the flame holes 362, 363, or 364 in theflame holder 360, an entire length of the flame becomes shorter, andmore amount of secondary air is introduced to the split short flames,with an increased mixing effect of the flames with the air that enhancescombustion, thereby achieving a perfect combustion, with blue flames ina stable flame state.

In other words, as the flame is split into a plurality of flames, anentire surface area of the flames is increased, with a relativelyincreased contact area with ambient air, i.e., the secondary air, thecombustion of gas is made more effectively, to achieve the perfectcombustion.

Moreover, the flame holder 360 divides between an inside and an outsideof the mixing tube 24, to prevent a reverse direction flame, and toprevent the flame from becoming unstable by an external influence.

Meanwhile, in the drying process again, the external air introduced intoan inside of the guide funnel 20 is heated, and turned into heated airas the gas is burned thus, and introduced into the drying chamber 5through the hot air supply duct 12.

The hot air introduced into the drying chamber 5 inside of the drum 1absorbs moist contained in laundry, passes through the lint filter 14again, and is blown toward the discharge pipe 19 by the blower 17through the lint duct 15.

In the meantime, the flame holder 360 may be rotatably fitted to aninside of the enlarged part 24 a of the outlet side of the mixing tube24. That is, the flame holder 360 may be provided with an additionaldriving source (not shown) for continuous rotation during operation, sothat the gas sprayed through the flame holder 360 forms turbulence.

A gas burner for a dryer in accordance with a fifth preferred embodimentof the present invention will be explained, with reference to theattached drawings. Alikely, parts identical to the related art will begiven the same reference symbols.

FIG. 10 illustrates a perspective disassembled view of gas burner for adryer in accordance with a fifth preferred embodiment of the presentinvention, FIG. 11A illustrates a perspective view of key parts of anoutlet side of a mixing tube seen from ‘A’ direction in FIG 10, and FIG.11B illustrates a perspective view of an outlet side of a mixing tubeseen from ‘A’ direction in FIG. 10, showing another embodiment of theflame holder.

As shown, there is a gas tube 32 connected to a gas nozzle 30 whichsprays gas for combustion. The gas nozzle 22 has a valve 30 fittedthereto for controlling spray of gas received through the gas tube 32,and a spray amount of the spray when the gas is sprayed.

There is a mixing tube 24 in front of the gas nozzle 22. The mixing tube24 has a mixing passage 240 therein for mixing the gas from the gasnozzle 22 and primary air. The mixing tube 24 has section designed suchthat a flow passage sectional area of the mixing tube 24 becomes thesmaller as it goes from an inlet side to an outlet side, and thenbecomes gradually the larger, again. The gas sprayed from the gas nozzle22 enters into the inlet of the mixing tube 24, together with theprimary air.

There is an igniter 50 at an outlet side of the mixing tube 24 forigniting the gas from the mixing passage 240 of the mixing tube 24. Theigniter 50 of ceramic is heated as a current is provided thereto, andignites the gas mixed, and discharged with the primary air. The igniter50 is either fitted to the mixing tube 24, or supported, separately.

There is a semispherical flame holder 460 at an outlet side of themixing tube 24 having a variety of forms of flame holes 462, 464, and465 in a face thereof for spraying the gas mixed with the primary air.The flame holder 460 is fitted so as to be recessed toward the inlet ofthe mixing tube 24, and has a circular flame hole 462 in a central partof the spherical surface, a plurality of slit form of flame holes 464around the circular flame hole in a radial direction, and circular flameholes 465 between the slit form of flame holes 464 for sustaining theflame.

In the meantime, the slit form of the flame hole may have a form of aconvex lens seen from a side as shown in FIG. 11A, or a crescent asshown in FIG 11B.

It is preferable that ratios of areas of the circular flame hole 462 inthe central part of the spherical surface, the slit form of flame holes464, and the circular flame holes 465 for sustaining a flame are set byan experiment.

The circular flame hole 462 in the central part of the sphericalsurface, the slit form of flame holes 464, and the circular flame holes462 for sustaining the flame spray the gas mixed with the primary airreceived through the mixing passage 240, to form a flame, of which mainflame is formed by the slit form of flame holes 464 and the circularflame hole 462 in the central part of the spherical surface duringcombustion.

In the present invention, owing to the semispherical form of the flameholder 460 recessed toward the inlet side of the mixing tube 24, aninitial ignition capability is enhanced since the gas escaped from thedifferent flame holes in the flame holder 460 gather at a center part ofthe outlet of the mixing tube 24 to a certain extent, that increases anamount of the mixed gas staying around the igniter 50, and reduces aflow speed of the gas.

Moreover, in the present invention, as the main flame is split into aplurality of flames by the plurality of slit form of flame holes 464 andthe circular flame hole 462 in the central part of the sphericalsurface, with an increased surface area of the flame on the whole,supply of the secondary air becomes more smooth. Especially, thecircular flame holes 465 between the slit forms of flame holes 464 serveto sustain the main flame.

In the meantime, the mixing tube 24 is fitted tilted upward at an anglewith reference to a horizontal plane as it goes from the inlet side tothe outlet side, so that a tube axis direction of the mixing tube is inagreement with a direction of flame in advance.

The operation of the foregoing fifth embodiment of the present inventionwill be explained, with reference to the embodiments shown in FIGS. 10,and 11A–11B.

For having a drying process progressed in a dryer, it is required toelevate a temperature of air introduced into the drying chamber 5 as thegas is burned. For this, gas is sprayed into the mixing tube 24 throughthe gas nozzle 22.

Along with the gas, primary air is introduced into the mixing tube 24.Accordingly, the gas and the primary air are mixed, and flow along thepassage inside of the mixing tube 24.

Then, the gas (i.e., a mixed gas) mixed with the primary air as the gasand the primary air flow along the inside passage of the mixing tube 24is split, and sprayed through the flame holes 462, 464, or 465 of thesemispherical flame holder 460 fitted to the outlet side of the mixingtube 24 so as to be recessed toward the inlet side. The mixed gassprayed thus is ignited as the mixed gas receives heat from the igniter50 provided adjacent to the flame holder 460.

Then, drying hot air is produced continuously as combustion is made, asthe mixed gas is kept sprayed through the flame holes 462, 464, and 465in the flame holder 460 in a split state. In this instance, the flameformed by the combustion of gas is split into a plurality of flames bythe slit form of flame holes 464, the circular flame hole 462 in acentral part of a spherical surface, and the circular flame holes 465between the slit form of flame holes 464.

According to this, in the present invention, a total flame lengthbecomes shorter, and a contact area with the secondary air becomeslarger.

That is, as the mixed gas discharged through the outlet side of themixing tube 24 is split through the flame holes 462, 463, and 464 in theflame holder 460, an entire length of the flame becomes shorter, andmore amount of secondary air is introduced to the split short flames,with an increased mixing effect of the flames with the air, therebyachieving a perfect combustion, with blue flames in a stable flamestate.

In other words, as the flame is split into a plurality of flames, anentire surface area of the flames is increased, with a relativelyincreased contact area with ambient air, i.e., the secondary air, thecombustion of gas is made more effectively, to achieve the perfectcombustion.

Moreover, the flame holder 460 divides between an inside and an outsideof the mixing tube 24, to prevent a reverse direction flame, and toprevent the flame from becoming unstable by an external influence.

Thus, as the flame is shortened, and the combustion is made effectivelyto achieve perfect combustion, the present invention can prevent thelifting in which an ignition point of the flame is positioned far froman outlet of the mixing tube 24, and the overheating of the air to besupplied to the drying chamber 5 in advance.

Meanwhile, in the drying process again, the external air introduced intoan inside of the guide funnel 20 is heated, and turned into heated airas the gas is burned thus, and introduced into the drying chamber 5through the hot air supply duct 12.

The hot air introduced into the drying chamber 5 inside of the drum 1absorbs moist contained in laundry, passes through the lint filter 14again, and is blown toward the discharge pipe 19 by the blower 17through the lint duct 15.

In the meantime, FIG. 12 illustrates a perspective disassembled view ofgas burner for a dryer in accordance with a sixth preferred embodimentof the present invention, wherein it can be noted that this is a case afitting position of the semispherical flame holder 460 explained in theforegoing embodiment is changed.

That is, different from the foregoing embodiment, the semisphericalflame holder 460 is positioned in front of the outlet of the mixing tube24 by a holding part 466.

In the meantime, FIG. 13A illustrates a perspective view of an outletside of a mixing tube seen from ‘B’ direction in FIG. 12, wherein formsand positions of the flame holes in the spherical surface of the flameholder 460 are identical to the case of FIG. 11A, of which explanationwill be omitted, accordingly.

FIG. 13B illustrates a perspective view of an outlet side of a mixingtube seen from ‘B’ direction in FIG. 12, showing another embodiment ofthe flame holder, wherein forms and positions of the flame holes in thespherical surface of the flame holder 460 are identical to the case ofFIG. 11B, of which explanation will be omitted too, accordingly.

Meanwhile, the flame holder 460 may be rotatably fitted to an inside ofthe outlet side of the mixing tube 460. That is, the flame holder 460may be fitted so as to be kept to rotate during operation by a separatedriving source (not shown) so that the gas sprayed through the flameholder 460 forms turbulence.

A gas burner for a dryer in accordance with a seventh preferredembodiment of the present invention will be explained, with reference tothe attached drawings. Alikely, parts identical to the related art willbe given the same reference symbols.

FIG. 14 illustrates a perspective disassembled view of gas burner for adryer in accordance with a seventh preferred embodiment of the presentinvention, and FIG. 15 illustrates a perspective view of an outlet sideof a mixer seen from ‘A’ direction in FIG. 14.

Referring to FIGS. 14 and 15, there is a gas tube 32 connected to a gasnozzle 30 which sprays gas for combustion. The gas nozzle 22 has a valve30 fitted thereto for controlling spray of gas received through the gastube 32, and a spray amount of the spray when the gas is sprayed.

There is a mixing tube 24 in front of the gas nozzle 22. The mixing tube24 has a mixing passage 240 therein for mixing the gas from the gasnozzle 22 and primary air. The mixing tube 24 has section designed suchthat a flow passage sectional area of the mixing tube 24 becomes thesmaller as it goes from an inlet side to an outlet side, and thenbecomes gradually the larger, again. The gas sprayed from the gas nozzle22 enters into the inlet of the mixing tube 24, together with theprimary air.

There is an igniter 50 at an outlet side of the mixing tube 24 forigniting the gas from the mixing passage 240 of the mixing tube 24. Theigniter 50 of ceramic is heated as a current is provided thereto, andignites the gas mixed, and discharged with the primary air. The igniter50 is either fitted to the mixing tube 24, or supported, separately.

There is a flame holder 560 in front of an outlet side of the mixingtube 24. The flame holder 560 has an annular hub 561 with a centralcircular flame hole 562, and blades 565 fitted at fixed intervals on anouter circumference of the hub 561 along a circumferential direction forsplitting the flame.

In this instance, the blades 565 are formed to have an angle twistedwith respect to a plane of the hub 561 for circulating the flames oncesplit as the gas passes between the blades.

The flame holder 560 can be positioned in front of the outlet of themixing tube as the holding part 566 extended from one side of the hub561 is fixed to the outlet side of the mixing tube.

It is preferable that a diameter of the circular flame hole 562, and awidth of the blade 565 are set by an experiment.

In the present invention, the flame holder 560 serves the gas, mixedwith the primary air as the gas passes through the mixing flow passage240, to be sprayed and burned, wherein a main flame is formed by themixed gas (gas mixed with the primary air) sprayed through the circularflame hole 562 in the central part of the hub 561 and openings betweenthe blades 565.

In this instance, in the present invention, an initial ignitioncapability is enhanced since an amount of the gas momentarily stayingbehind the flame holder 560 before passing through the flame holder 560is increased while a speed of the gas is dropped by the holding part 566extended from the hub 561 of the flame holder 560.

Moreover, in the present invention, as the main flame is split into aplurality of flames by the circular flame hole 562 in the central partof the flame holder and the plurality of the blades 565, with anincreased surface area of the flame on the whole, supply of thesecondary air becomes more smooth.

Especially, the twisting of blades 565 with respect to a hub 561 planeat a fixed angle provides a circulating force to the flame once split bycombustion of the gas passing through the blades, that makes thecombustion more effective.

In the meantime, the mixing tube 24 is fitted tilted upward at an angleas it goes from the inlet side to the outlet side, so that a tube axisdirection of the mixing tube is in agreement with a direction of flame,naturally.

The operation of the foregoing seventh embodiment of the presentinvention will be explained, with reference to FIGS. 14, and 15.

For having a drying process progressed in a dryer, it is required toelevate a temperature of air introduced into the drying chamber 5 as thegas is burned. For this, gas is sprayed into the mixing tube 24 throughthe gas nozzle 22.

Along with the gas, primary air is introduced into the mixing tube 24.Accordingly, the gas and the primary air are mixed, and flow along thepassage inside of the mixing tube 24.

Then, the gas (i.e., a mixed gas) mixed with the primary air as the gasand the primary air flow along the inside passage of the mixing tube 24is split, and sprayed through the circular flame hole 562, and openingsbetween the blades 565 of the flame holder 560 provided on the outletside of the mixing tube 24. The mixed gas sprayed thus is ignited as themixed gas receives heat from the igniter 50 provided adjacent to theflame holder 560.

Then, drying hot air is produced continuously as combustion is made, asthe mixed gas is kept sprayed through the circular flame hole 562, andthe blades 565 of the flame holder 560 in a split state.

According to this, in the present invention, a total flame lengthbecomes shorter, and a contact area of the flame with the secondary airbecomes larger.

That is, as the mixed gas discharged through the outlet side of themixing tube 24 is split through the circular flame hole 562, and theblades 565 of the flame holder 560, an entire length of the flamebecomes shorter, and more amount of secondary air is introduced to thesplit short flames, with an increased mixing effect of the flames withthe air to enhance combustion, thereby achieving a perfect combustion,with blue flames in a stable flame state.

In other words, as the flame is split into a plurality of flames, anentire surface area of the flames is increased, with a relativelyincreased contact area with ambient air, i.e., the secondary air, thecombustion of gas is made more effectively, to achieve the perfectcombustion.

Moreover, the flame holder 560 divides between an inside and an outsideof the mixing tube 24, to prevent a reverse direction flame, and toprevent the flame from becoming unstable by an external influence.

Thus, as the flame is shortened, and the combustion is made effectivelyto achieve perfect combustion, the present invention can prevent thelifting in which an ignition point of the flame is positioned far froman outlet of the mixing tube 24, and the overheating of the air to besupplied to the drying chamber 5 in advance.

Meanwhile, in the drying process again, the external air introduced intoan inside of the guide funnel 20 is heated, and turned into heated airas the gas is burned thus, and introduced into the drying chamber 5through the hot air supply duct 12.

The hot air introduced into the drying chamber 5 inside of the drum 1absorbs moist contained in laundry, passes through the lint filter 14again, and is blown toward the discharge pipe 19 by the blower 17through the lint duct 15.

In the meantime, the flame holder 560 may be rotatably fitted to aninside of the outlet side of the mixing tube. That is, the flame holder560 may be fitted so as to be kept to rotate during operation by aseparate driving source (not shown) so that the gas sprayed through theflame holder 560 forms turbulence.

Next, a gas burner for a dryer in accordance with an eighth preferredembodiment of the present invention will be explained, with reference tothe attached drawings. Alikely, parts identical to the related art willbe given the same reference symbols.

FIG. 16 illustrates a perspective disassembled view of a gas burner fora dryer in accordance with an eighth preferred embodiment of the presentinvention, and FIG. 17 illustrates a perspective view of an outlet sideof a mixer seen from ‘A’ direction in FIG. 16.

Referring to FIGS. 16 and 17, there is a gas tube 32 connected to a gasnozzle 30 which sprays gas for combustion. The gas nozzle 22 has a valve30 fitted thereto for controlling spray of gas received through the gastube 32, and a spray amount of the spray when the gas is sprayed.

There is a mixing tube 24 in front of the gas nozzle 22. The mixing tube24 has a mixing passage 240 therein for mixing the gas from the gasnozzle 22 and primary air. The mixing tube 24 has section designed suchthat a flow passage sectional area of the mixing tube 24 becomes thesmaller as it goes from an inlet side to an outlet side, and thenbecomes gradually the larger, again. The gas sprayed from the gas nozzle22 enters into the inlet of the mixing tube 24, together with theprimary air.

There is an igniter 50 at an outlet side of the mixing tube 24 forigniting the gas from the mixing passage 240 of the mixing tube 24, andis either fitted to the mixing tube 24, or supported, separately.

The igniter 50 of ceramic is heated as a current is provided thereto,and ignites the gas mixed, and discharged with the primary air.

There is a flame holder 660 in front of an outlet side of the mixingtube 24. The flame holder 660 includes a vertical face 661 having acentral flame hole 662, and sidewall faces 663 at both edges thereofeach extended backward to rear of the flame holder 660 to form a width,and a horizontal face 664 extended backward from top of the verticalface 661 perpendicular thereto.

That is, the flame holder 660 has a “┐” formed plate structure, andserves for forming the flame divided in four directions, i.e., indirections of the circular flame hole 662 in the vertical face 661, bothsides of the vertical face 661, and an underside of the vertical face661.

The sidewall faces 663 at opposite edges of the vertical face 661 of theflame holder 660 are formed by cutting opposite side parts of an edgewhere the vertical face 661 and the horizontal face 664 meet, andbending the opposite side parts backward.

The flame holder 660 can be positioned in front of the outlet of themixing tube 24 spaced a distance away therefrom as the holding part 665extended from a rear end of the horizontal face 664 is fixed to anoutlet side of the mixing tube 24.

It is preferable that an area ratio of the circular flame hole 662 andthe vertical face 661, and the like are set by an experiment.

The flame holder 660 serves the gas, mixed with the primary air as thegas passes through the mixing flow passage 240, to be sprayed andburned, wherein the mixed gas (gas mixed with the primary air) is splitin directions of the circular flame hole 662 in the central part of thevertical face 661, the underside of the vertical face 661, and outersides of the sidewall faces 663, and ignited, to form a main flame.

In this instance, in the present invention, an initial ignitioncapability is enhanced since an amount of the mixed gas colliding ontothe vertical face 661 of the flame holder 660 and momentarily stayingbehind the flame holder 660 before passing through the flame holder 660is increased while a speed of the mixed gas is dropped.

Moreover, in the present invention, as the main flame is split into aplurality of flames by the flame holder 660 having the vertical face 664with the central circular flame hole 662 formed therein, with anincreased surface area of the flame on the whole, supply of thesecondary air to the flame becomes more smooth.

In the meantime, the mixing tube 24 is fitted tilted upward at an angleas it goes from the inlet side to the outlet side, so that a tube axisdirection of the mixing tube is in agreement with a direction of flame,naturally.

The operation of the foregoing eighth embodiment of the presentinvention will be explained, with reference to FIGS. 16, and 17.

For having a drying process progressed in a dryer, it is required toelevate a temperature of air introduced into the drying chamber 5 as thegas is burned. For this, gas is sprayed into the mixing tube 24 throughthe gas nozzle 22.

Along with the gas, primary air is introduced into the mixing tube 24.Accordingly, the gas and the primary air are mixed, and flow along thepassage inside of the mixing tube 24.

Then, the gas (i.e., the mixed gas) mixed with the primary air as thegas and the primary air flow along the inside passage of the mixing tube24 is split, and sprayed through the circular flame hole 662, left andright sides of the horizontal face, and the underside of the horizontalface of the flame holder 660 provided on the outlet side of the mixingtube 24. The mixed gas sprayed thus is ignited as the mixed gas receivesheat from the igniter 50 provided adjacent to the flame holder 660.

Then, drying hot air is produced continuously as combustion is made, asthe mixed gas is kept sprayed through the circular flame hole 662, leftand right sides of the horizontal face, and the underside of thehorizontal face of the flame holder 660 in a split state.

According to this, a total flame length becomes shorter, and a contactarea of the flame with the secondary air becomes larger.

That is, as the mixed gas discharged through the outlet side of themixing tube 24 is split in four directions by the horizontal face havingthe circular flame hole 662 formed therein of the flame holder 660, anentire length of the flame becomes shorter, and more amount of secondaryair is introduced to the split short flames, with an increased mixingeffect of the flames with the air to enhance combustion, therebyachieving a perfect combustion, with blue flames in a stable flamestate.

In other words, as the flame is split into four flames, an entiresurface area of the flames is increased, with a relatively increasedcontact area with ambient air, i.e., the secondary air, the combustionof gas is made more effectively, to achieve the perfect combustion.

Moreover, the flame holder 660 divides between an inside and an outsideof the mixing tube 24, to prevent a reverse direction flame, and toprevent the flame from becoming unstable by an external influence.

Thus, as the flame is shortened, and the combustion is made effectivelyto achieve perfect combustion, the present invention can prevent thelifting in which an ignition point of the flame is positioned far froman outlet of the mixing tube 24, and the overheating of the air to besupplied to the drying chamber 5 in advance.

Meanwhile, in the drying process again, the external air introduced intoan inside of the guide funnel 20 is heated, and turned into heated airas the gas is burned thus, and introduced into the drying chamber 5through the hot air supply duct 12.

The hot air introduced into the drying chamber 5 inside of the drum 1absorbs moist contained in laundry, passes through the lint filter 14again, and is blown toward the discharge pipe 19 by the blower 17through the lint duct 15.

Lastly, a gas burner for a dryer in accordance with a ninth preferredembodiment of the present invention will be explained, with reference tothe attached drawings. Alikely, parts identical to the related art willbe given the same reference symbols.

FIG. 18 illustrates a perspective disassembled view of a gas burner fora dryer in accordance with a ninth preferred embodiment of the presentinvention, FIG. 19 illustrates a front view of an outlet side of a mixerseen from ‘A’ direction in FIG. 18, and FIG. 20 illustrates aperspective view of an outlet side of a mixer seen from ‘A’ direction inFIG. 18.

FIG. 21 illustrates a perspective, disassembled, back side view of FIG.20, and FIG. 22 illustrates a section of a flame holder across a lineI—I in FIG. 19.

Referring to FIGS. 18–22, there is a gas tube 32 connected to a gasnozzle 30 which sprays gas for combustion. The gas nozzle 22 has a valve30 fitted thereto for controlling spray of gas received through the gastube 32, and a spray amount of the spray when the gas is sprayed.

There is a mixing tube 24 in front of the gas nozzle 22. The mixing tube24 has a mixing passage 240 therein for mixing the gas from the gasnozzle 22 and primary air. The mixing tube 24 has section designed suchthat a flow passage sectional area of the mixing tube 24 becomes thesmaller as it goes from an inlet side to an outlet side, and thenbecomes gradually the larger, again. The gas sprayed from the gas nozzle22 enters into the inlet of the mixing tube 24, together with theprimary air.

There is an igniter 50 at an outlet side of the mixing tube 24 forigniting the gas from the mixing passage 240 of the mixing tube 24, andis either fitted to the mixing tube 24, or supported, separately.

The igniter 50 of ceramic is heated as a current is provided thereto,and ignites the gas mixed, and discharged with the primary air.

There is a flame holder 760 in front of an outlet side of the mixingtube 24. The flame holder 760 includes an annular hub 761 having acentral circular flame hole 762, and a plurality of blades 765, and 767fitted to an outer circumference of the hub 761 at fixed intervals alonga circumferential direction thereof for splitting the flame.

Each of the blades 765, and 767 has a backward bent part 765 a, or 767a, and one 767 of the blades has an arc longer by more than two times ofthe other blades 765.

The annular hub 761 is convexed forward.

The backward bent part 765 a, or 767 a is sloped at an angle θ in arange of 10–30 degrees with respect to an axis passing through thecircular flame hole 762 of the hub 761.

The flame holder 760 can be positioned in front of the outlet of themixing tube 24 as the holding part 766 extended from one side of the hub761 is fixed to an outlet side of the mixing tube 24.

It is preferable that a diameter of the circular flame hole 762, areasof the blades 765 and 767, and the like are set by an experiment.

In the meantime, the flame holder 760 serves the gas, mixed with theprimary air as the gas passes through the mixing flow passage 240, to besprayed and burned, wherein the main flame is formed by the mixed gas(gas mixed with the primary air) sprayed through the circular flame hole762 in the central part of the hub 761, and openings between the blades765, and 767.

That is, in the present invention, as the main flame is split into aplurality of flames by the circular flame hole 762, and the blades 765,and 767, with an increased surface area of the flame on the whole,supply of the secondary air to the flame becomes smooth.

Especially, in the embodiment, of the blades formed along thecircumferential direction of the hub 761 of the flame holder 760, sinceone of the blade 767 has an arc length longer than other blades 765 bymore than two times, with a larger blade area, and there are thebackward bent parts 765 a and 767 a at fore ends of the blades 765 and767, increasing an amount of the mixed gas momentarily staying behindthe flame holder 760 before passing through the flame holder 760 whiledropping a speed of the mixed gas, an initial ignition capability isenhanced, making the ignition easy. That is, the flame holder 760 of thepresent invention improves an initial ignition characteristic.

In the meantime, the mixing tube 24 is fitted tilted upward at an angleas it goes from the inlet side to the outlet side, so that a tube axisdirection of the mixing tube is in agreement with a direction of flame,naturally.

The operation of the foregoing eighth embodiment of the presentinvention will be explained, with reference to FIGS. 18 to 22.

For having a drying process progressed in a dryer, it is required toelevate a temperature of air introduced into the drying chamber 5 as thegas is burned. For this, gas is sprayed into the mixing tube 24 throughthe gas nozzle 22.

Along with the gas, primary air is introduced into the mixing tube 24.Accordingly, the gas and the primary air are mixed, and flow along thepassage inside of the mixing tube 24.

Then, the gas (i.e., the mixed gas) mixed with the primary air as thegas and the primary air flow along the inside passage of the mixing tube24 is split, and sprayed through the circular flame hole 762, andopenings between the blades 765 and 767 of the flame holder 760 providedon the outlet side of the mixing tube 24. The mixed gas sprayed thus isignited as the mixed gas receives heat from the igniter 50 providedadjacent to the flame holder 760.

Then, drying hot air is produced continuously as combustion is made, asthe mixed gas is kept sprayed in a split state by the circular flamehole 762, and the blades 765 and 767 of the flame holder 760.

According to this, a total flame length becomes shorter, and a contactarea of the flame with the secondary air becomes larger.

That is, as the mixed gas discharged through the outlet side of themixing tube 24 is sprayed, with the flame split by the circular flamehole 662, and the blades 765, and 767 of the flame holder 760, an entirelength of the flame becomes shorter, and more amount of secondary air isintroduced to the split short flames, with an increased mixing effect ofthe flames with the air to enhance combustion, thereby achieving aperfect combustion, with blue flames in a stable flame state.

In other words, as the flame is split into a plurality of flames, anentire surface area of the flames is increased, with a relativelyincreased contact area with ambient air, i.e., the secondary air, thecombustion of gas is made more effectively, to achieve the perfectcombustion.

Moreover, the flame holder 760 divides between an inside and an outsideof the mixing tube 24, to prevent a reverse direction flame, and toprevent the flame from becoming unstable by an external influence.

Especially, since there is a boss with a length ‘d’ in an inner side ofthe hub 761 extended to a rear side of the flame holder 760, reversingof flame is delayed, to prevent the reversing of the flame at the end.

Thus, as the flame is shortened, and the combustion is made effectivelyto achieve perfect combustion, the present invention can prevent thelifting in which an ignition point of the flame is positioned far froman outlet of the mixing tube 24, and the overheating of the air to besupplied to the drying chamber 5 in advance.

Meanwhile, in the drying process again, the external air introduced intoan inside of the guide funnel 20 is heated, and turned into heated airas the gas is burned thus, and introduced into the drying chamber 5through the hot air supply duct 12.

The hot air introduced into the drying chamber 5 inside of the drum 1absorbs moist contained in laundry, passes through the lint filter 14again, and is blown toward the discharge pipe 19 by the blower 17through the lint duct 15.

In the meantime, the flame holder 760 may be rotatably fitted to aninside of the outlet side of the mixing tube 24. That is, the flameholder 760 may be provided with an additional driving source (not shown)for continuous rotation during operation, so that the gas sprayedthrough the flame holder 360 forms turbulence.

INDUSTRIAL APPLICABILITY

As has been explained, the gas burner for a dryer in accordance withanyone of the preferred embodiments of the present invention is designedto split a flame into many flames by means of the flame holder providedto an outlet side of the mixing tube. Accordingly, a length of the flamecan be made shorter, that prevents lifting of the flame, and entrance ofthe flame into an inside of the drum.

Moreover, the enlarged contact area of the flame with the secondary aircoming from the split of the flame increases an amount of air introducedinto the flame, that enhances a mixing effect of the flame with thesecondary air, to achieve perfect combustion, that reduces production ofhazardous gas, and stabilizes flame.

Along with this, the flame holder prevents a combustion state in eitherone of front/rear parts of the flame holder being transferred to theother side, preventing reversing of fire, thereby helping stabilizationof the flame.

Accordingly, the present invention is very useful for industry.

1. A gas burner for a dryer comprising: a gas nozzle for receiving and spraying a gas; a mixing tube for mixing the gas sprayed from the gas nozzle and primary air; an igniter fitted to an outlet side of the mixing tube for igniting the gas mixed with the primary air passed through the outlet of the mixing tube; and a flame holder at an outlet side of the mixing tube for splitting the gas mixed with the primary air and spraying the gas mixed with the primary air, wherein the flame holder includes a central hole and a first plurality of holes disposed at a periphery of the flame holder with a plurality of elongated apertures located between the central hole and the first plurality of holes, wherein the flame holder further includes a second plurality of circular flame holes between the elongated apertures in a radial direction at fixed intervals to be concentric with respect to the central hole.
 2. A gas burner as claimed in claim 1, wherein the second plurality of circular flame holes have the same diameters.
 3. A gas burner as claimed in claim 1, wherein the elongated apertures are slit forms of flame holes arranged in a radial direction in a surface of the flame holder; and the first plurality of boles are rectangular.
 4. A gas burner as claimed in claim 1, wherein the second plurality of circular flame holes between the central circular flame hole of the flame holder and the elongagted apertures have the same diameters.
 5. A gas burner as claimed in claim 1, wherein the central hole and the first plurality of holes have different diameters.
 6. A gas burner as claimed in claim 1, wherein the mixing tube has a venturi structure, and includes an enlarged part an outlet of the mixing tube wherein the flame holder is fitted to an inside of the enlarged part.
 7. A gas burner as claimed in claim 6, wherein the enlarged part at the outlet of the mixing tube is formed as one unit with the mixing tube, or as a detachable separate piece.
 8. A gas burner as claimed in claim 1, wherein the flame holder is fitted so as to be located in front of an outlet of the mixing tube as a holding part extended from a side of the mixing tube. 